Create throne-inheritance.cpp

Author: kamyu104

C++/throne-inheritance.cpp

@@ -0,0 +1,43 @@
+// Time:  ctor:    O(1)
+//        birth:   O(1)
+//        death:   O(1)
+//        inherit: O(n)
+// Space: O(n)
+
+class ThroneInheritance {
+public:
+    ThroneInheritance(string kingName) : king_name_(kingName) {
+        
+    }
+    
+    void birth(string parentName, string childName) {
+        family_tree_[parentName].emplace_back(childName);
+    }
+    
+    void death(string name) {
+        dead_.emplace(name);
+    }
+    
+    vector<string> getInheritanceOrder() {
+        vector<string> result;
+        vector<string> stk = {king_name_};
+        while (!empty(stk)) {  // preorder traversal
+            const auto node = move(stk.back()); stk.pop_back();
+            if (!dead_.count(node)) {
+                result.emplace_back(node);
+            }
+            if (!family_tree_.count(node)) {
+                continue;
+            }
+            for (int i = size(family_tree_[node]) - 1; i >= 0; --i) {
+                stk.emplace_back(family_tree_[node][i]);
+            }
+        }
+        return result;
+    }
+
+private:
+    string king_name_;
+    unordered_map<string, vector<string>> family_tree_;
+    unordered_set<string> dead_;
+};